This invention relates to a process for producing an oxygen-containing hydrocarbon compound from carbon monoxide and hydrogen, such as, for example, synthesis gas. More particularly, the present invention concerns reaction of carbon monoxide and hydrogen in the presence of a catalyst comprising a combination of rhodium-iridium-lithium supported on a carrier having a specific surface area of more than 150 m.sup.2 /g.
The preparation of two-carbon atom oxygenated compounds acetic acid, acetaldehyde and ethanol from carbon monoxide and hydrogen, such as, for example, synthesis gas is known.
In general, when a gaseous mixture of carbon monoxide and hydrogen, such as synthesis gas, contacts with a catalyst, a variety of products are formed. The products include saturated aliphatic hydrocarbons ranging from methane to paraffin; unsaturated aliphatic hydrocarbons including alpha-olefin; aromatic hydrocarbons having 6-10 or more carbon atoms; alcohols ranging from methanol to higher alcohol having about 20 carbon atoms; aldehydes and fatty acids. Particulars of the products depend upon nature of the catalysts employed.
In general, it had been difficult to selectively form the desired compounds while suppressing formation of the undesirable compounds by reacting carbon monoxide with hydrogen. In order to achieve the above mentioned purpose, much research on catalysts has been made. There are many patents and patent applications on catalysts for such reaction. For example, Japanese Patent Publication (kokai) No. 55-57527; U.S. Ser. No. 551,661 dated Jan. 16, 1975 and U.S. Ser. No. 437,141 dated Jan. 28, 1974; and U.S. Pat. Nos. 4,014,913 patented on Mar. 29, 1977, 4,224,236 patented on Sept. 23, 1980 and 4,288,558 patented on Sept. 8, 1981 disclose that rhodium-containing catalysts are used for selectively producing two carbon atoms oxygenerated compounds from carbon monoxide and hydrogen.
The present inventors have carried out the reaction of carbon monoxide and hydrogen in the presence of a rhodium catalyst. It was found that though the rhodium catalyst allows selective formation of two carbon atom oxygenerated compounds and suppresses undesirable by-products, such as carbon dioxide, methane, etc., catalytic activity of the rhodium catalyst is low. In addition, it was also found that when the rhodium catalyst is used for the reaction between carbon monoxide and hydrogen, acetaldehyde is formed as a main component. Therefore, production of acetic acid by reacting carbon monoxide with hydrogen in the presence of the rhodium catalyst is improper. Since rhodium is expensive, it is important to improve the catalytic activity of rhodium catalyst and its selectivity to the desired products in the reaction.